What To Do When You Find a Black Widow Spider?

A female black widow spider making a web outdoors.

Black widow spiders are venomous spiders that are found with relative frequency in and around homes around the world. 

Though they are not responsible for many human deaths, their bites often cause painful wounds that can become dangerous if not treated promptly.

What should you do when you find a black widow spider? If possible, leave the spider alone and prevent it from leaving the area until you can apply a pesticide. Do not attempt to catch and relocate it, and avoid the temptation to squish it as this may result in a bite. Call a professional for infestations.

Knowing what steps you should follow upon finding a black widow will help you remain calm and stay safe while effectively getting rid of the pest.

Let’s examine the safest route to take when dealing with a black widow.

There’s no question that spiders can be intimidating. Learn all you can about prevention and elimination methods so that you can confidently handle any spider problem. Click here to learn all about dealing with spiders of all shapes and sizes.

What Are Black Widow Spiders?

Many types of spiders and even certain insects are similar in appearance to the black widow, so it is important to know which spider you’re dealing with.

(Are spiders insects? Find the answer here.)

Appearance

The term black widow comes from the perception that the female eats the male after mating with him, which actually happens only with certain species of black widows in nature and is not the norm.

As with most species of spiders, females are the bigger and more brightly colored gender. They are the ones that are most commonly recognized as black widows.

Female black widows are dark, shiny black in color with a bright red or orange hourglass marking on the underside of the abdomen. They are about an inch and a half long with black legs.

Male black widow spiders are about half the size of females. They are black or purple in color and usually have yellow, orange, or red bands and spots on their backs. 

Juveniles, both male and female, are lighter in color with similar markings to the adult male. 

Fun fact: As far as size is concerned in the spider world, black widows are actually rather tiny. Other spiders grow to be much, much larger, like the beautiful banana spider whose webs can reach 6 feet across!

Habits

The web of the black widow is usually constructed near ground level. It is messy and irregular, often confused for a web that has been abandoned by its owner. 

Black widow spiders usually look for areas near the ground or floor where they can hide, preferring to stay under baseboards, shoes, or steps. 

These reclusive spiders look for man-made structures where they can be sheltered from the elements.

You might find a black widow inside a shoe, in a crawl space, under a stack of wood, beneath garden pavers, inside cardboard boxes, in unused closets or in your garage. 

(Garages are often favorite shelters for a multitude of spiders. Learn how to easily clean up their messy webs and get rid of your uninvited garage guests in this article.)

Typically, black widows will choose warm, dark, dry places to build webs.

They are more active in warm weather when temperatures are 70°F or higher, though they can survive in much colder environments. 

Because their webs are built so low to the ground, their diet consists mostly of non-flying arthropods such as millipedes, ants, and other spiders, along with cockroaches, moths, and beetles.

Though their bite is venomous, black widows prefer to flee instead of bite. Unless they are provoked or feel the need to protect their eggs, black widows will choose to hide. 

They will quickly abandon any area where humans show up. This makes it difficult to tell when or if there is an infestation in the home since black widows are rarely seen.

Bite

A black widow bite generally only comes from the female as she attempts to protect her eggs or feels threatened.

Symptoms include fever, nausea, a rise in blood pressure, and excessive sweating. 

The bite might not be painful immediately but will have two red dots in the middle of the spot. Most of those who are bitten begin feeling symptoms within a few hours. 

These symptoms typically last a few days before subsiding with professional medical care.

If you believe you have been bitten by a black widow spider, seek medical help immediately.

Unfortunately, black widows are not the only dangerous spiders of which you need to be aware. Take a look at these other spiders that pose a threat so you’ll know what to watch for.

What to Do When You Find a Black Widow

It can be easy to give in to feelings of panic when you first spot that classic red mark, but there’s really no need to be anxious.

Remember that black widows are not “out to get you,” and remaining calm will let you think clearly and respond in the correct way.

What is the correct way? That exactly what you’ll learn in the following.

Do Not Provoke It

Since black widows are not aggressive, you should not give them a reason to become angry. Their natural inclination will be to flee – let the spider follow its instinct.

Do not try to catch the spider in an attempt to verify its identity. 

In most cases, it is best to allow the spider to retreat to safety and avoid the area until you are ready to use a pesticide.

However, if you, family members, or pets are in danger of being bitten, you can use your vacuum cleaner’s hose attachment to suck it up.

Carefully dispose of the bag’s contents in a bag, seal it securely, and place it in an outdoor trash receptacle.

Many people use a shoe, fly swatter, or similar item to squish black widows when they find them.

Although this will immediately eliminate the threat (if you are accurate in swatting), you may miss your target, provoke the spider, and risk a bite. It’s usually not worth taking the chance.

Perhaps you’ve heard that the best course of action upon coming face to face with a spider is to douse it with hairspray.

While hairspray can kill a spider, this approach isn’t recommended when you’re dealing with a potentially dangerous spider like the black widow.

Seal off the Area

Look for any possible way the black widow could move to another part of the house. 

  • Patch all holes in the drywall.
  • Apply appropriate weather stripping to all exterior doors.
  • Do not leave doors or windows open.
  • Leave all items in that room or area; do not move them around.

The goal is to safely make sure the spider (or spiders) cannot move to another part of your home.

Use a Pesticide

Pesticides are products that contain some sort of toxic element. This toxic element is concentrated at an amount appropriate to the targeted pest. 

The toxic element in most pesticides is harmful to all living things but is adjusted to only harm organisms of a certain size. 

So, while a toxic chemical in a pesticide is enough to kill a black widow spider, it might only cause a minor reaction in a human. 

When fighting black widows, only apply your own pesticides when you are confident the spider is out of reach and you are not dealing with a full-blown infestation. 

If you cannot guarantee these things, pause this step and call a professional exterminator.

Always wear appropriate personal protective equipment when handling chemicals, including gloves and face masks. Keep the pesticide out of the reach of children and pets.

Many people choose to use a fogger to broadcast pesticides over a large area. However, many common, general-purpose foggers will not get the job done.

If you choose to use a fogger, head over to our article “Best Fogger for Spiders” first to see which options will actually work.

Other than foggers, there are two different types of pesticides you should consider when fighting a black widow: contact pesticide or pesticide dust. 

Our Complete Guide To Getting Rid of Spiders Quickly is packed with the best prevention and elimination tactics. Don’t miss it!

Contact Pesticide

As its name implies, this type of pesticide is a chemical that kills on contact. It is designed to be sprayed directly on the pest – in this case the black widow – or its web. 

Most contact pesticides are liquid and come with their own spraying device. Others come concentrated and must be diluted with water in a pump sprayer. 

Terro Spider Killer spray comes in an aerosol can and is designed specifically for black widows, brown recluses, and hobo spiders.

Additionally, it kills many of the pests that black widows eat including ants, roaches, and beetles.

So, this spray will not only eliminate your target pest but will also get rid of the food sources that were luring black widows inside in the first place.

The active ingredients are pyrethrins and deltamethrin.

Terro 16 oz. Spider Killer Aerosol Spray - 2 Spray...

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Demon Max Insecticide is another good option. This product contains cypermethrin, a strong chemical that works on virtually all types of spiders.

Demon Max comes heavily concentrated, so it must be diluted and used with a pump sprayer.

Demon Max Insecticide Pint 25.3% Cypermethrin

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Finally, Miss Muffet’s Revenge is a fantastic product that uses bifenthrin to eliminate black widow spiders.

It also has residual pesticide properties, which means it creates a barrier to keep spiders out of your home. 

Wet & Forget Miss Muffet's Revenge Spider Killer

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Pesticide Dust

A pesticide dust is a type of residual pesticide, which means it retains its potency for long periods of time. It is handy because it does not dry up over time, so it can stay in place longer. 

Most dusts are designed to be shot underneath floorboards or into gaps that other pesticides can’t reach. They often require a separate bellows device.

Bayer Delta Dust is a powerful pesticide that lasts up to a year if applied correctly. It does not collect moisture and will not clump. 

Use a bellows to shoot this product around your garage, basement, or crawlspace to quickly kill any black widow spider.

Be careful though; this is a powerful product that should not be used anywhere children or pets will have access.

Call a Professional if Necessary

If you see evidence of a black widow infestation – silky egg sacs, more than 10 webs, or multiple sightings of live spiders – do not attempt to use pesticides yourself.

Instead, immediately call a trusted, highly-rated exterminator.

Additionally, call an exterminator if you see evidence of a black widow more than a week after applying pesticides to the area.

Most exterminators will have a list on their website of all the different pests they can handle. 

Summary

If you see a black widow spider, do not provoke it or attempt to catch it. Make sure it cannot move into any other area of your home. 

Purchase a contact pesticide or pesticide dust that will kill spiders and apply it carefully.

Do not hesitate to contact a professional exterminator if the pesticide does not work or if there appears to be an infestation.

Always use caution when dealing with potentially dangerous spiders or chemicals.

Don’t miss out on important spider prevention steps and elimination guidelines. See all of our spider articles here.

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